(* Copyright (C) 2010 School of Software Engineering, 
 * University of Science and Technology of China.
 *
 * This code is released under a BSD-style license.
 * See the file LICENSE for details.
 *)

signature TRACE =
sig

    val enter: string -> unit
    val lookup: string -> bool
    val trace: string * ('a -> 'b) 
               * ('a -> Layout.t) * ('b -> Layout.t) -> 'a -> 'b
end
